Typically, (host) vehicles may be equipped with radars systems used to classify the environment in the vicinity of the vehicle such as to e.g. detect moving or static objects around the vehicle. Such systems are used to for example, to estimate the motion state of other vehicles for automotive perception systems and can be used in Active Safety, Driver Assistance and Autonomous Driving applications.
Typically, such systems may include Doppler radar methodology where reflected radar signals are detected and analyzed in the frequency domain, typically by applying Fast Fourier Transform methodology. So, Doppler radar measurements are usually extracted by applying the Fast Fourier Transform to the baseband signal captured from the environment. Typically results are divided into a number of frequency ranges—referred to often as bins. The span of frequencies is limited by design. This results in a limited interval of unambiguous range rate measurement. Measurements beyond that span of frequencies fall into FFT bins that do not directly correspond to the velocity of the target. This is the phenomenon of range rate aliasing. Determination of the appropriate aliasing period or range rate is required to correct the measurement of the relative velocity; i.e. between the host vehicle and a target (such as another vehicle or object). The procedure of such a correction is called de-aliasing. The standard approach to resolving range rate measurement aliasing is to track the target in time and identify the appropriate aliasing period based on the change of the target position.
It is an object of the invention to provide an improved method for the de-aliasing of range rate instantaneously in a single time instance. The fundamental condition for applicability of the proposed solution is that there are several point detections captured by the Doppler radar from a single target (such target is usually referred to as a distributed/rigid target).
So aspects of the invention provides a method for instantaneous de-aliasing of range rate measurements (of Doppler radar) for distributed targets
This invention applies (e.g.) a plausibility check of velocity profile estimation to determine the appropriate aliasing period. The complete procedure for instantaneous de-aliasing is described including the necessary assumptions.
It is an object of the invention to provide a method of determining aliasing range rates which is not based on tracking or filtering and therefore does not require any motion model and no initialization stage is required. Solutions provide calculation of de-aliased range rates based on a single time instance measurement of a Doppler radar.